Gemini surfactant-stabilized cubosomes for enhanced topical delivery of 5-fluorouracil in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is a prevalent non-melanoma skin cancer. Topical chemotherapy offers a non-invasive alternative to surgical treatments, yet the therapeutic efficacy of conventional agents like 5-fluorouracil is hindered by poor skin permeability and systemic side effects. In this study, we developed a gemini-surfactant-stabilized cubosomal gel (OF12-GEL) for enhanced topical delivery of 5-fluorouracil. The optimized cubosomes (OF12) exhibited a particle size of 134.4 nm, PDI 0.23, zeta potential +76.1 mV, and 51.3% entrapment efficiency. OF12-GEL achieved 41% release at 24 h and increased skin deposition to 323.7 μg/cm², nearly 3-fold higher than free 5-FU (114.1 μg/cm²). In A431 cells, OF12 showed a lower IC₅₀ (0.77 μg/mL) than free 5-FU (1.15 μg/mL) and enhanced cellular uptake. In vivo , OF12-GEL significantly suppressed tumor growth in both DMBA-induced SCC rats and A431 xenograft mice, reducing tumor volume by and improving survival to 60%, and markedly downregulating BCL-2, Ki67, TNF-α, and ABCB1. OF12-GEL was non-irritant (PII = 0.33). These findings demonstrate a potent, safe, and targeted nanocarrier-based topical therapy for cSCC.